JP2005191889A - Communication electric power control method and electric power communication modem - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent unnecessary radiation of electromagnetic wave and an interference to another electrical device and the like by performing communication between PLC modems at a minimum connectable communication electric power level. <P>SOLUTION: When starting communication, PLC modems A and B which desire to communicate confirm whether or not the communication is possible by transmitting and receiving an synchronous signal SYN and an ACK signal by using a communication electric power level 7 whose communication electric power is the largest. When the communication is possible, the PLC modems A and B confirm whether or not the communication is possible by lowering the communication electric power level one by one (sequence 301-306) similarly. When the communication is disabled (sequence 307-310) due to a reduction of the communication power level, the communication electric power level is raised by one, whether or not the communication is possible is confirmed (sequence 301-313), the communication is established at this communication electric power level, and actual communication is started. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a communication power control method and a power line communication modem in a power line communication (PLC) modem, and more particularly to a power line communication modem capable of reducing unnecessary radiation of electromagnetic waves from a power line. The present invention relates to a communication power control method and a power line communication modem.

  In recent years, home appliances such as various home appliances have a power line communication function in homes, etc., and monitor and control these home appliances from a master unit constituted by a PC, etc. There has been proposed a system that enables access to the above-described master unit via the Internet, and allows monitoring and controlling home devices from the outside. In addition, it enables high-speed signals to be handled by power line communication, and multimedia information such as video information and audio information from ISPs (Internet Service Providers) via public communication networks including the Internet is real-time A system that enables display on a display device has also been proposed.

Also, a conventional technique for measuring the line quality of a power line when performing data transmission using the power line and ensuring the transmission quality is described in, for example, Patent Document 1 and the like.
JP-A-6-291700

  None of the above power line communication systems according to the prior art considers control of communication power when a power line communication modem performs communication, and performs communication with fixed communication power. There is a problem that electromagnetic waves of 4 MHz to 20 MHz that are normally used carrier frequencies are unnecessarily radiated and may interfere with other electric devices.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and to make it possible to variably control the communication power used by a power communication modem (hereinafter referred to as a PLC modem) for communication. It is an object of the present invention to provide a communication power control method and a power line communication modem in a PLC modem that can perform communication with the communication power of the PLC modem and prevent unnecessary radiation of electromagnetic waves.

  According to the present invention, in the communication power control method in a power line communication modem, the level of usable communication power is set in a plurality of stages, and the communication power level set in the plurality of stages at the start of communication is set to the higher side. This is achieved by confirming whether or not it is possible to connect to the device on the other side using the communication power whose communication power level has been lowered in order from the communication power, and performing communication at the lowest connectable communication power level.

  According to the present invention, in the communication power control method in a power line communication modem, the level of usable communication power is set in a plurality of stages, and at the start of communication, the communication power level set in the plurality of stages is set. This is achieved by using the communication power that has been increased from the lowest communication power level in order to check whether it is possible to connect to the device on the other side, and communicating at the lowest communication power level that can be connected. .

  In addition, in the above, the purpose is to check whether the connection with the counterpart device is possible or not based on whether the synchronization signal and the ACK signal sent from the counterpart device have been normally received. Is achieved.

  Further, the object is to use a means for setting a plurality of levels of usable communication power in a power line communication modem, and communication power on the higher communication power level set in the plurality of stages at the start of communication. This is achieved by performing communication with the lowest communication power level that can be connected, and a means for confirming whether or not connection with the device on the other side is possible using communication power whose communication power level has been lowered in order.

  Further, the object is to provide means for setting a plurality of levels of usable communication power in a power line communication modem, and communication power on the lower communication power level set in the plurality of stages at the start of communication. This is achieved by performing communication with the lowest communication power level that can be connected, and a means for confirming whether or not the connection with the counterpart device can be made using the communication power whose communication power level has been increased in order.

  Furthermore, in the above, the purpose is to check whether the means for confirming whether the connection with the counterpart device is possible or not has successfully received the synchronization signal and the ACK signal sent from the counterpart device. Is achieved by

  According to the present invention, it is possible to variably control the communication power used by the PLC modem for communication, to perform communication with the minimum necessary communication power, and to prevent unnecessary radiation of electromagnetic waves. Can do.

  Embodiments of a communication power control method and a PLC modem according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration example of a power line communication system to which the present invention is applied, and FIG. 2 is a block diagram showing a configuration of a PLC modem according to an embodiment of the present invention. 1 and 2, 11 to 15 are PLC modems, 16 is a base station, 17 is a switch hub, 18 is a media converter, 19 is a network, 20 is a power line, 21 is a USB line, and 22 is an Ethernet (registered trademark) line. , 23 is a CPU, 24 and 27 are SRAMs, 25 is an EEPROM, 26 is a flash ROM, 28 is an AISC, 29 is a PLC dedicated IC, 30 is a front end, 31 is an AC insertion unit, and 32 is a display unit.

  The power line communication system according to the embodiment of the present invention shown in FIG. 1 includes a plurality of PLC modems 11 to 15 connected to a power line 20 as shown in FIG. The switch hub 17 and the media converter 18 are connected, and the PLC modem 11 is connected to an external network 19 including the Internet through these. Each of the PLC modems 12 to 15 is connected to a PC, home appliance, or the like (not shown), and the PC, the home appliance, etc. can communicate with each other via the PLC modem and the power line 20. Further, when a PC is connected to the PLC modem, the PC is connected to the own PC, such as a PLC modem, a power line 20, a PLC modem 11, a base station 16, a switch hub 17, a media converter 18, an external network. It is possible to communicate with a server such as a provider (not shown) via 19 to receive various information and to exchange mail.

  The power line communication system as described above may be provided in a home or the like, or may be provided as one system in an entire apartment house such as an apartment. Furthermore, it may be installed for all departments of the company.

  As shown in FIG. 2, each of the PLC modems 11 to 15 includes a USB line 21 and an Ethernet (registered trademark) line 22 that are interfaces with a PC, home appliances, and the like, and a CPU 23 that controls the entire modem, Communication between the SRAM 24, EEPROM 25, flash ROM 26, AISC 28, SRAM 27 used by the AISC 28, PLC dedicated IC 29, and power line 20 for storing programs and data necessary for various processes in the CPU 23. A front end 30 that performs control, an AC insertion unit 31 that superimposes a communication signal on the power line 20 via an AC power outlet or takes out a communication signal on the power line 20, and a display unit 32 such as an LED are provided. It is configured.

  As described above, the EEPROM 25 and the flash ROM 26 include a processing program executed by the CPU 23 and a communication method for performing communication with the power line 20 necessary for the PLC modem shown in FIG. Information on the communication power level for signal transmission, information on the data transmission speed, and the like.

  In the embodiment of the present invention, in the PLC modem configured as described above, the CPU 20 controls the level of communication power for signal transmission, and is unnecessary from the power line of the carrier wave carrying the communication signal transmitted on the power line 20. Next, a communication power control method according to an embodiment of the present invention will be described.

  FIG. 3 is a sequence chart illustrating the communication power control operation according to the embodiment of the present invention. In the example shown in FIG. 3, the communication power level is set to seven levels from level 7 to level 1 (level 7 is the maximum level), and the minimum that can perform reliable communication from these seven communication power levels. This is an example of processing when the communication power level is searched for and communication is performed according to the level.

(1) Now, it is assumed that the PLC modem A tries to start communication with the PLC modem B. In this case, the PLC modem A first transmits a communication signal including the address of the PLC modem B and the synchronization signal SYN to the power line 20 using the communication power level 7 which is the communication power level with the largest communication power ( Sequence 301).

(2) The PLC modem B monitors the communication signal sent on the power line 20, and if it can confirm the communication signal whose address is addressed to its own modem, it captures it and responds with the synchronization signal SYN and ACK as a response. A communication signal including the signal is sent to the power line 20 together with the address of the PLC modem A. At that time, PLC modem B performs the above-described response using communication power level 7 which is the communication power level with the largest communication power (sequence 302).

(3) PLC modem A receives the response communication signal from PLC modem B transmitted in sequence 302 and transmits an ACK signal to PLC modem B. With the processing so far, the initial connection is confirmed between the PLC modem A and the PLC modem B (sequence 303).

(4) Thereafter, the communication power control sequence is started, and the PLC modem A lowers the power level to the communication power level 6 which is the next highest communication power level, and uses this power level 6 Then, a communication signal including the address of PLC modem B and synchronization signal SYN is transmitted to power line 20 (sequence 304).

(5) If the PLC modem B can confirm the communication signal addressed to its own modem in the same manner as in the case of the sequence 302, it captures it and uses the power level 6 to the PLC modem A. In response to the response, PLC modem A that has received the response transmits an ACK signal to PLC modem B in the same manner as in sequence 303 (sequences 305 and 306).

(6) The PLC modems A and B exchange communication signals similar to those in the sequences 304 to 306 while reducing the communication power level. For example, the communication signals are normally exchanged up to the communication power level 3. Suppose you were able to do it.

(7) The PLC modem A further reduces the power level to the communication power level 2 which is the next largest communication power level, and uses the power level 2 to use the PLC modem B address and synchronization signal. A communication signal including SYN is transmitted to the power line 20 (sequence 307).

(8) If the PLC modem B monitors the communication signal sent on the power line 20 and tries to confirm the communication signal whose address is addressed to the own modem, the PLC signal cannot be confirmed. Modem B will not respond to anything. The PLC modem A waits for a certain time for a response from the PLC modem B to the transmission of the communication signal including the address of the PLC modem B and the synchronization signal SYN, and when the response is not obtained, again, the PLC modem A sets the same power level 2 again. The communication signal including the address of the PLC modem B and the synchronization signal SYN is transmitted to the power line 20 (sequences 308 and 309).

(9) The PLC modem A waits for a predetermined time for a response from the PLC modem B to the re-transmission of the communication signal including the address of the PLC modem B and the synchronization signal SYN. The communication power level is raised to the communication power level 3, which is the communication power level that can be established, and the communication power level 3 is used to generate a communication signal including the address of the PLC modem B and the synchronization signal SYN. The data is sent to the power line 20 (sequence 310, 311).

(10) If the PLC modem B can confirm the communication signal addressed to its own modem in the same way as in the case of the sequence 302, it captures it and uses the power level 3 to send it to the PLC modem A. In response to the response, PLC modem A that has received the response transmits an ACK signal to PLC modem B in the same manner as in sequence 303 (sequences 312 and 313).

(11) By the communication power control sequence from the above-described sequence 304 to 311, the lowest communication power level that can be communicated between the PLC modem A and the PLC modem B is found to be level 3. PLC modem A and PLC modem B use this communication power level to start communication with each other.

  The above-described sequence in the embodiment of the present invention checks whether communication is possible while lowering the communication power level in order from the communication power level 7 which is the communication power level with the largest communication power, and the lowest possible communication is possible. Although described as finding the communication power level, the present invention enables communication by confirming whether communication is possible while increasing the communication power level in order from the communication power level 1 which is the communication power level with the lowest communication power. It is also possible to find the lowest communication power level. In this case, a sequence similar to the above-described sequences 307 to 309 is performed while increasing the communication power level, and the communication power level that is confirmed to be able to communicate first is defined as the communication power level for actual communication. do it.

  In the above-described embodiment of the present invention, the communication power level is set to seven levels and the communication power is controlled. However, the number of the communication power level to be set is arbitrarily determined. Can do.

  It is desirable to control the communication power in the power line communication modem as described above every time communication between the power line communication modems is performed. The reason for this is that various electrical devices are connected to the power line, and their usage changes with time. With this change, the impedance of the power line seen from the power line communication modem changes, and the transmission quality of the power line. This is because the level of communication power that can be communicated between modems varies each time communication is performed.

  According to the embodiment of the present invention described above, communication between power line communication modems can be performed with the lowest communication power level that can be connected to each other, so that unnecessary radiation of electromagnetic waves can be prevented. It is possible to prevent interference with other electrical devices.

It is a block diagram which shows the structural example of the power line communication system to which this invention is applied. It is a block diagram which shows the structure of the PLC modem by one Embodiment of this invention. It is a sequence chart explaining the control operation | movement of the communication power in embodiment of this invention.

Explanation of symbols

11-15 PLC modem 16 Base station 17 Switch hub 18 Media converter 19 Network 20 Power line 21 USB line 22 Ethernet (registered trademark) line 23 CPU
24, 27 SRAM
25 EEPROM
26 Flash ROM
28 AISC
29 PLC dedicated IC
30 Front end 31 AC insertion section 32 Display section

Claims (6)

  In the communication power control method in the power line communication modem, a plurality of levels of usable communication power are set, and at the start of communication, the communication power level is set in order from the communication power of the higher communication power level set in the plurality of stages. A communication power control method comprising: confirming whether or not connection with a partner apparatus is possible using the reduced communication power, and performing communication at a minimum connectable communication power level.   In the communication power control method in the power line communication modem, the level of usable communication power is set in a plurality of stages, and at the start of communication, the communication power level is set in order from the communication power of the lower communication power level set in the plurality of stages. A communication power control method comprising: confirming whether connection with a partner apparatus is possible using the increased communication power, and performing communication at a minimum connectable communication power level.   2. The confirmation as to whether the connection with the counterpart device is possible or not is made by checking whether the synchronization signal and the ACK signal sent from the counterpart device have been normally received. Or the communication power control method of 2.   In the power line communication modem, the communication power level is lowered in order from the communication power level set in a plurality of stages and the communication power on the higher communication power level set in the plurality of stages at the start of communication. A power line communication modem characterized by comprising means for confirming whether or not a connection with a device on the other party side is possible using the communication power, and performing communication at the lowest connectable communication power level.   In the power line communication modem, the communication power level is increased in order from the communication power level set in a plurality of stages and the communication power on the lower communication power level set in the plurality of stages at the start of communication. A power line communication modem characterized by comprising means for confirming whether or not a connection with a device on the other party side is possible using the communication power, and performing communication at the lowest connectable communication power level. The means for confirming whether the connection with the counterpart device is possible is performed depending on whether or not the synchronization signal and the ACK signal sent from the counterpart device have been normally received. Item 6. The power line communication modem according to Item 4 or 5.

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